Osmorregulação dos peixes - Vertebrados - Biologia

Summary

In this informative session, we explore osmoregulation in aquatic animals, emphasizing the differences between marine and freshwater species. The speaker explains the osmotic pressure variations that influence water movement in fish, detailing how marine fish must consume seawater and excrete excess salts through their gills, while freshwater fish absorb water through their skin and eliminate excess water in dilute urine. Additionally, the session highlights how cartilaginous fish like sharks maintain fluid balance through urea synthesis, adapting to their environment as osmo conformers. This engaging discussion prepares students for further exploration of osmoregulation concepts.

Takeaways

• 🌊 Osmosis involves the movement of water from a hypotonic environment (less concentrated) to a hypertonic environment (more concentrated).
• 🐟 Marine fish must drink seawater to compensate for water loss due to osmotic pressure from their environment.
• 🧂 Marine fish eliminate excess salts through their gills via active transport, which requires energy.
• 🚽 The urine of marine fish is isotonic, meaning it has a similar concentration to seawater, helping to retain water.
• 🌊 Freshwater fish experience the opposite osmotic pressure, with water naturally entering their bodies.
• 💧 Freshwater fish do not need to drink water, as they absorb it through their skin and gills.
• 🔄 To prevent dilution of their internal fluids, freshwater fish actively absorb salts from their environment.
• 💧 The urine of freshwater fish is hypotonic, meaning it is less concentrated than the surrounding water and is produced in larger volumes.
• 🦈 Sharks and other cartilaginous fish (like rays) maintain the tonicity of their blood similar to seawater by synthesizing and retaining urea.
• 🔄 Sharks are classified as osmoconformers because their body fluids are isotonic with their environment, allowing for equilibrium between water intake and loss.

Q & A

What is osmosis?

Osmosis is the movement of water from a hypotonic environment (less concentrated) to a hypertonic environment (more concentrated) across a semipermeable membrane.

What is osmoregulation?

Osmoregulation refers to the processes by which aquatic animals control their internal water and salt concentrations to maintain homeostasis.

How do marine bony fish (osteichthyes) manage osmoregulation?

Marine bony fish manage osmoregulation by drinking seawater to compensate for water loss through osmosis and actively excreting excess salts through their gills.

Why do marine fish produce isotonic urine?

Marine fish produce isotonic urine to minimize further water loss to the surrounding hypertonic environment, ensuring they do not dehydrate.

How do freshwater fish adapt their osmoregulation mechanisms?

Freshwater fish adapt by not drinking water, as they gain sufficient water through osmosis, and they actively absorb salts through their gills while excreting dilute, hypotonic urine.

What role do gills play in osmoregulation for both marine and freshwater fish?

In marine fish, gills excrete excess salts, while in freshwater fish, gills actively absorb necessary salts from the diluted external environment.

What are chondrichthyes, and how do they regulate their osmotic balance?

Chondrichthyes, such as sharks and rays, are cartilage fish that maintain their osmotic balance by synthesizing and accumulating urea in their blood to match the osmolarity of seawater.

What is the difference between osmoconformers and osmoregulators?

Osmoconformers maintain internal fluid concentrations similar to their external environment (like chondrichthyes), while osmoregulators actively control their internal concentrations against external osmotic pressure (like osteichthyes).

How does the water concentration inside freshwater fish compare to their environment?

The water concentration inside freshwater fish is higher (more concentrated) than in their surrounding environment, leading to water influx through osmosis.

What is the significance of urea synthesis in chondrichthyes?

The synthesis of urea in chondrichthyes is significant because it helps to maintain an osmotic balance with their marine environment, allowing them to avoid dehydration and regulate their internal fluids.